True The frames under our trucks are tougher than the iron in the gates of hell. But the BEST frame Ford EVER built was under a Louisville....called it a "drop frame"....it's waht's under my old Lousiville. 1973 frame, STILL has all the ORIGINAL rivets in it
built Ford tough!
As a professional driver, I can tell you this. Getting UP the hiss is NOT the problem. You have enough power to haul an appropriate sized load up that with your pickup and trailer. The problem exists when going downhill. People let their speed get up too much, and try to nail the brakes. It's like trying to stop on ice....you won't. Even with that exhaust brake, you won't have enough braking power to stop if you let your speed creep up.
General rule of thumb. When transversing a downhill grade, go down itn in the SAME gear toy would climb UP it loaded. If you come up in third, go DOWN in it third with the same load on. I have NEVER had that rule come back and bite me yet.